SU566768A1 - Method of extractional photometric detection of lanthanium - Google Patents

Description

one

The invention relates to the field of analytical chemistry and can be used to determine lanthanum in solutions containing rare earth elements of yttrium, yttrium and scandium.

The known method of determining lanthanum using organic reagents and subsequent photometric measurement of the complex compound formed.

Arsenazo, for example, is used as an organic reagent.

However, this method does not have sufficient sensitivity.

Introduction diphenylguanidini increases the sensitivity of the reaction slightly.

In addition, this method can only determine the sum of rare-earth elements, since the reagent Arsenazo III forms almost equally strong complexes with all REEs, regardless of their atomic number.

The closest to the invention in its technical essence and the achieved result is the method of extraction-photometric determination of lanthanum using chlorophosphonazo III as an organic reagent and n-butanol as the extractant of the forming compound. The reagent is introduced into the initial solution at pH 1.1 -1.5. The degree of extraction of the complex 90-

92%. The sensitivity of the determination of lanthanum in this way is characterized by a molar repayment coefficient of 91,000. Furthermore, the method does not allow to determine

lanthanum in the presence of rare earth elements of yttrium group, yttrium and scandium with a ratio of lanthanum and scandium more than 1: 10.

The aim of the invention is to determine lanthanum, which has a higher

sensitivity and selectivity.

This is achieved by the proposed method of extraction-photometric determination of lanthanum, including its conversion into a complex compound with an organic reagent, chlorophosphonaz III, extraction of the complex with n-butanol and subsequent photometric measurement.

Claims (3)

Distinctive features of the process are that complex IV is introduced into the initial solution at pH 2.8-3.1, then -chlorophosphonaz III and, after the latter is added, a solution of diphenylguanidine chloride is introduced. At the same time, the rare earth elements of the yttrium group form strong complexonates with complexone IV, which does not affect the reaction of chlorophosphonaz III with lanthanum. The resulting lanthanum ternary ion associate with chlorophosphonazo III with diphenylguanidine chloride is extracted with n-butanol, and the optical density of the butanol extract is measured. Example 1. Method for determining laitap in the presence of scandium (up to the molar ratio La:: 500) without correction for the masked iop. To the sample solution pH 3.0 were added 10 ml of a 2.5-10 M solution of complexone IV, 1.0 ml of a 6.8-10 M solution of chlorophosphonaz III, approximately 10 ml of a buffer mixture solution with a pH of 3.0 (CHsCOONa + HCl), 1.0 ml of 1 M solution of diphenylguanidine chloride. The volume of the solution is adjusted to 25 ml with a buffer mixture, and the solution is stirred. After 30 minutes, the solution is transferred to a separatory funnel, and the product formed is extracted with 25 ml of n-butanol. Chlorophosphonazo III gives a pink extract, in the presence of lanthanum, the color of the extract becomes blue-green. The butanol extract is centrifuged for 2-3 minutes to completely separate from traces of the aqueous phase. The optical density of the butanol extract was measured on a spectrophotometer at A, 670 mmc in a cuvette cm, relative to the extract from the solution containing all of the indicated components with the exception of the sample solution. The content of lanthanum is found from the calibration curve, which is plotted in the concentration range of lanthanum 1-10- -8-10- M. Example 2. Method for determination of lanthanum in the presence of Yb (Lu) up to the molar ratio La: Yb (Lu) l: 20,000 corrected for the masked ion. Previously, the sum of lanthanum and ytterbium (lutetium), which practically constitutes the content of ytterbium (lutetium), is determined in the sample to be analyzed. The sample size is selected so that the concentration of ytterbium (lutetium) in the aqueous solution from which extraction is carried out with n-butanol is 2.0-10 M. To the sample solution (solution volume not more than 2 ml) is added 2.0 ml of 7.5-10 M solution of complexone IV, 1.0 ml of 6.8-10 M solution of chlorophosphonazo P1, approximately 10 ml of buffer mixture with pH 2.9 and 1.5 ml of 1 M solution of diphenylguanidine chloride. The volume of the solution is made up to 25 ml with a buffer mixture and stirred. After 30 minutes, the solution is transferred to a separatory funnel, and the product formed is extracted with 10 ml of n-butanol. The butanol extract is transferred to a test tube and centrifuged for 2-3 minutes to completely separate traces of the aqueous phase. The optical density of the butanol extract was measured on a spectrophotometer at I 670 mcc in a cuvette with cm relative to the extract from the solution, containing all of these components except for the sample solution, as well as ytterbium (lutetium) at a concentration of 2 ,. The content of lanthanum is found from the calibration curve, which is plotted in the concentration range of lanthanum I-IO -5-10 M in the presence of ytterbium (lutetium), which corresponds to the interval of optical density of 0.1 - 0.5. The concentration of ytterbium (lutetium) is the same in all solutions and should be 2.0-10-2 m. Example 3. Method for determination of lanthanum in the presence of Y (Dy) up to a molar ratio of La: Y (Dy) of 1: 2000 corrected for the masked ion. Previously, the sum of lanthanum and yttrium (dysprosium) is determined in the sample to be analyzed, which practically makes up the content of yttrium (dysprosium). The sample size is selected so that the concentration of yttrium (dysprosium) in the aqueous solution from which n-butanol is extracted is 2.0-10 M. To the sample solution pH 3.0 is added 2.0 ml 0.75 M solution of complexone IV, 1.0 ml of 6.8-10 M solution of chlorophosphonaz III, approximately 10 ml of a buffer mixture with pH 3.0 and 1.5 ml of 1 M solution of diphenylguaidini chloride. The volume of the solution is made up to 25 ml with a buffer mixture and stirred. After 30 minutes, the solution is transferred to a separatory funnel, and the product formed is extracted with 25 ml of n-butanol. The butanol extract is transferred to a test tube and centrifuged for 2-3 minutes. The optical density of the butanol extract was measured on a spectrophotometer at I 670 mmc in a cuvette with cm relative to the extract from the solution, containing all of these components except for the sample solution, as well as yttrium (dysprosium) at a concentration of 2.0-10 M. The content of lanthanum is found from a calibration curve, which is plotted in the concentration range of lanthanum 1 M in the presence of yttrium (dysprosium), which corresponds to an optical density range of 0.1-0.5. The yttrium (dysprosium) concentration in all the solutions is the same and should be 2.0-10-3 M. The sensitivity of the proposed method is characterized by a molar ratio of the lanthanum complex of 16,000. The method allows to determine lanthanum in the presence of scandium, yttrium and rare-earth metals. elements of the yttrium subgroup up to the La: Me ratio of 1: 500 (Sc), 1: 6 (Y, Dy), 1: 200 (Yb, Lu) without correction for the masked one and 1: 50,000 (Se), 1: 2000 ( Y, Dy) 1: 20000 (Yb, Lu) corrected for the masked ion. Claims Extraction-photometric determination of lanthanum, including the transfer of an antenna to a complex compound with an organic reagent, chlorophosphonase III, extraction of the complex by n-butanol, and subsequent photometry, characterized in A pH of 2.8-3.1 is administered by complex IV, then chlorophosphonazo III, and then a solution of diphenylguanidine chloride.